Cell death is roughly classified into apoptosis and necrosis. Apoptosis is a form of death of cells constituting a body of a multicellular organism. Apoptosis refers to controlled and regulated cellular suicide which is actively caused to keep an individual in better condition. On the other hand, necrosis refers to cell death caused by a deterioration of environment inside and outside cells due to an external injury, poor blood circulation, or the like.
Necrosis refers to local death of living tissue.
Unlike normal death, in necrosis, only cells constituting a part of a body become extinct. The causes of necrosis include infection, physical disruption, chemical injury, and a reduction in blood flow. Necrosis due to a reduction in blood flow is particularly called infarction. Even when cells are dead, if normal cells and tissue, such as blood cells, skin, and mucosal epithelium of digestive tract, are continually replenished without leaving a functional disorder or histological abnormality, such cell death is not called necrosis. The dead tissue is finally removed by an immune system of an organism, and a defective part is compensated by regeneration or fibrosis of the original tissue.
For testing and studying the cells, it is necessary to culture cells isolated from tissue. In recent years, the cell culture is carried out for a variety of purposes such as drug discovery/development, production of drugs, basic tests in regenerative medicine, and evaluation of drugs. The cell culture is indispensable in fields related to biotechnology. The research and development speed depends on the adhesion ability of cells to be cultured in a cell incubator, since the adhesion ability is an extremely important factor for the differentiation/proliferation ability of the cells. Further, cell lines to be used for the culture test are extremely expensive, which affects test cost directly.
It is known that, in the case of culturing cells in a cell culture chamber such as a petri dish made of plastic, a petri dish made of glass, a glass plate fixed into the chamber, or a well plate, a pH change due to carbon dioxide gas exhausted from cultured cells largely affects the activity of the cultured cells. In the conventional long-time culture, culture solution is periodically replaced by a worker, thereby keeping the activity of the cultured cells.
Further, Patent Document 1 proposes a cell culture chamber characterized by including a mass of projections each having an equivalent diameter of 10 nm to 1 mm formed on the surface of the cell culture chamber. Through the formation of a mass of projections, culture solution is allowed to spread over a lower part of the cells to promote the supply of nutritive substances necessary for the cells and the elimination of waste products discharged from the cells. In addition, the cells are brought into contact with the chamber by point contact, thereby preventing the cells from being damaged when the cells are removed.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2005-168494